Auto-sync with upstream branch master
    
    Upstream commit: e37c2cf299b61ce18f62852f6c5624c27829b610
    
    - Move _dl_open_check to its original place in dl_open_worker
    - Block signals during the initial part of dlopen
    - Remove all loaded objects if dlopen fails, ignoring NODELETE (#1395758)
    - Avoid late dlopen failure due to scope, TLS slotinfo updates (swbz#25112)
    - Avoid late failure in dlopen in global scope update (swbz#25112)
    - Lazy binding failures during dlopen/dlclose must be fatal (swbz#24304)
    - resolv: Implement trust-ad option for /etc/resolv.conf (#1164339)
    - dlsym: Do not determine caller link map if not needed
    - libio: Disable vtable validation for pre-2.1 interposed handles (swbz#25203)
    - ldbl-128ibm-compat: Add syslog functions
    - ldbl-128ibm-compat: Add obstack printing functions
    - ldbl-128ibm-compat: Reuse tests for err.h and error.h functions
    - ldbl-128ibm-compat: Add error.h functions
    - ldbl-128ibm-compat: Add err.h functions
    - ldbl-128ibm-compat: Add argp_error and argp_failure
    - sparc: Use atomic compiler builtins on sparc
    - Remove 32 bit sparc v7 support